Remove the upper limit on midi_voices.

- Black MIDIs can be brutal, and there's really no reason that this needs
  to be artificially limited to a paltry 256 voices.

src/timidity/timidity.cpp

@@ -698,7 +698,7 @@ Renderer::Renderer(float sample_rate, const char *args)
 	if (def_instr_name.IsNotEmpty())
 		set_default_instrument(def_instr_name);
 
-	voices = clamp<int>(midi_voices, 16, 256);
+	voices = MAX(*midi_voices, 16);
 	voice = new Voice[voices];
 	drumchannels = DEFAULT_DRUMCHANNELS;
 }